1. Field of the Invention
The present invention relates to an apparatus for and a method of manufacturing a photographic paper which is capable of preventing a photographed image thereon from being copied unauthorizedly by an image reading device.
2. Description of the Related Art
There has recently been proposed and used a photographic paper with a matrix of dots, each about 0.1 mm across, formed as a latent image at a pitch of 2.25 mm on the entire surface thereof. The dots will be seen as yellow dots after the picture on the photographic paper is developed. The photographic paper has been developed to prevent a photographed image thereon from being duplicated unauthorizedly for the purpose of protecting copyrights of commercial photographers.
Recently available image reading devices have their performance greatly improved to the point where they can produce copies as comparable to photoprints. Stated otherwise, a copy of a photoprint can easily be produced by a modern image reading device, rather than going to the trouble of producing a photoprint from an original negative.
Since unauthorized duplication of a photoprint with an image reading device is illegal, some measures must be taken to prevent such unauthorized photoprint duplication. Unauthorized photoprint copying poses a social problem as it tends to reduce the income of commercial photographers.
One scheme for preventing the unauthorized photoprint duplication is to form a latent image of dots on a photographic paper, as described above. Specifically, an image reading device incorporates a function (software-implemented function) to detect a matrix of developed dots, and can detect a regular pattern of dots on a photographic paper. When the image reading device detects such dots on a photographic paper, the image reading device produces a warning indicating that copying the image on the photographic paper will be unauthorized photoprint duplication, and stops reading the image on the photographic paper.
The developed dots are invisible to the naked eye because they are very small in size and yellow in color. Therefore, the dots do not impair the quality of photoprints.